88 TII overheating on highway issue
 

My TII overheats on the highway or 40-50mph local driving after 15-20 mins. Temps are great when sitting idle and even went through a 2 hour dyno session with no issues at all. Problems arise only with constant load. Could it be:

A. airflow issue - FMIC covers the whole grill area on my OEM s4 bumper
B. thermostat
C. no fan shroud on my electric fan

Most likely A.

Not having a shroud with the efan is not good, but would actually be helping you at speed.

Do you have the factory underbelly tray?

no under tray. i assumed that if it was not an airflow issue because it wouldn't have the issue when i'm driving on the highway, or is that where i've gone wrong?

Airflow and possibly blocked/inefficient rad if its only at cruising speeds, when you have an endless supply of free air but constant partial engine load. Id check the ducting first. Make sure air coming through front of car has no where to go but through the rad. If that involves putting undertray on and sealing gaps around the edges with foam or whatever.

Ding ding ding...this is FC cooling 101, even without a FMIC.

thanks fellas. is the stock undertray the black plastic one or the small metal one?

Black plastic tray.

Or the aluminum pan coupled with the radiator cooling tray by our friend Landon at LRB Speed :)

that black plastic tray is long gone lol i will check out the LRB one. i know they also sell some heat vents that i also need.

What's the normal idle range and temp range? My 88 FC II idles at 850 and the temp needle doesn't go to half way point. Is that normal??

on my s4 cluster, the water temp will sit about 1/8th way up from cold start to warm up (car not moving) however, with my current issue it'll go halfway or maybe even slightly over after 15 mins of driving.

so it seems like lrb is sold out of their under trays, anyone have any suggestions for an alternative?

That is normal. S4 temp gauge is normal at 1/4-1/3, S5 normal at 1/2.

hey guys, i'm going to install a FMIC, i'm going to leave off the undertray and i plan on running an E-fan without a shroud. what do you guys think?

How old is your radiator? OEM or aftermarket? I had the same problem. Turned out my radiator was partially clogged. Bought a new koyo, problem solved. Intercooler directly in front of radiator, no tray or ducting.

Only e-fan you should be running is a 2 speed Ford Taurus, Probe, or similar with a proper thermo switch in place. The undertray is an absolute must. Front Mount Intercooler should not be a problem if you duct everything properly. Without that tray, you will overheat on the highway.

Thats just not true, sorry. It got to 110f here last year and i didnt see temps over 210f with my efan, doing 85mph on the freeway.

GREAT idea!

OP, Do you still have A/C? The condenser coil can heat soak and block airflow to the rad even when it is not in use. Get an undertray, and check out your fan situation, some fans can inhibit air flow.

Yes, if it goes past the 1/4 range, your overheating

Sure. If this was 5 years ago. The Taurus fan is probably the WORST efan you can use, besides the Black Magic. It was just one of the first mainstream OEM fans people were hacking into these cars.

My ebay fan worked great for the three years i owned my car. it would cool it from 205 to 195 in less than a minute.

Now i sold it and its going to work great for somebody else.

I'm a efan fan, so I don't doubt it. There's just better out there that what used to be toted as "the best", back in the day.

Lol.... im a efan fan too. Those OE fans can be so bulky.

i have a koyo. LBC is out for the next month and i haven't been able to find an under tray alternative yet. going to do a full coolant flush cause the car sat still for 4-5 years.

no a/c